Einri of Eire

Einri Ua Conchobair of Eire (26 December 1038-), also known by his English name Henry O'Connor of Ireland, was High King of Ireland from 1090. Einri, originally the Earl of Tyrconnell, succeeded in uniting Northern Ireland through military conquest before becoming the Petty King of Ulster, and he proclaimed himself "High King of Ireland" in 1090.

Unification of Ulaidh
Einri Ua Conchobair was born in Gartan, Tyrconnell (in present-day County Donegal, Ireland) on 26 December 1038 to the Clan O'Connor of Tyrconnell. Einri came from a powerful family, and he married Orlaith, having several children with her. In December 1066, Einri became Earl of Tir Chonaill after seizing power from the previous ruling clan, and he was the first O'Connor of Tyrconnell to hold a noble title. Einri appointed an array of talented courtiers to court positions, and he sent his chancellor to fabricate claims on nearby states in order to acquire casus bellis on the other nobles. Einri succeeded in doing so, and he waged a series of campaigns of conquest from the 1060s to the 1080s. Einri subjected Tir Eoghain, Ulster, and Airgialla to Tyrconnellian rule, and he gave fiefs to his sons Eochaid of Ulaidh (ruler of Ulster) and Focarta of Airgialla. Einri would consolidate his realms to become the Petty King of Ulster, and he ruled over the northern parts of Ireland for years.